1. Field of the Invention
The present invention relates to fluorene-based alternating polymers to be used as luminescent materials in manufacturing macromolecular electroluminescence (EL) devices, and more particularly relates to EL devices using such fluorene-based alternating polymers as light emitting materials.
2. Description of the Prior Art
Examples of EL elements which have been studied thus far, include inorganic semiconductors such as GaAs which have the advantages of being small in size, require little consumption of electric power, etc., and are currently being used as display devices having a small surface area, light emitting diode (LED) lamps, semiconductor lasers, and the like. However, in manufacturing such elements, extremely clean processing is required, and it is difficult to make LEDs of large surface area and it is difficult to obtain blue light having good efficiency. Furthermore, there are inorganic semiconductors having fluorescent ions of metal compounds added thereto, and inorganic EL elements made by dispersing inorganic semiconductors into high molecule compounds, but these cause problems in semiconductor stability not only because they require a high operating voltage but also because they operate under high electric fields.
However, as organic EL materials (Appl. Phys. Lett., 51, p.913 (1987) and macromolecular EL materials (Nature, 347, p.539(1990)) capable of overcoming such problems have recently been developed, advances in research in these fields are continuing to progress. When voltage is applied to an EL element, which is manufactured by depositing organic dyes (Japanese Laid-open Patent Publication Nos. 6-136360 and 7-26254), or by placing macromolecules having a conjugate double bond (Int""l Patent Publication Nos. WO92/03491, WO93/14177. And WO94/15368) between an anode and a cathode, holes from the cathode and electrons from the anode are introduced into the EL element. The holes and electrons move to a luminescent layer, and are coupled again with each other, thereby emitting light. Currently, efforts are being made to find applications of such EL elements for next generation flat panel color display devices, electrochemical cells, image sensors, photocouplers, and the like which use LEDs, which can replace cathode-ray tubes, gas plasma displays, liquid crystal displays currently being used. However, elements manufactured by deposition of organic dyes have problems in reproducibility and in making uniform films, and although macromolecule-based EL elements have overcome such problems to a certain degree, improved stability, efficiency and durability are still required for desired applications for practical commercial uses.
Poly(phenylene vinylene) (PPV), polythiophene (PTh) and polyphenylene-based macromolecules (Synth. Met. 50(1-3), p.491 (1992) and Adv. Mater., 4, p. 36 (1992)), are known as representative macromolecular luminescent materials which have been currently studied, but these materials have the disadvantage that the final material is insoluble in any organic solvent. Such materials may exhibit an improved processability by appropriate substituents introduced therein. Although PPV and PTh derivatives (Synth. Met., 62, p.35 (1994), Adv. Mater., 4, p.36 (1994), and Macromolecules, 28, p. 7525 (1995)), which emit diverse lights of blue, green and red colors, are known but the manufacturing process of such derivatives is very complicated, and they also exhibit problems in stability. Moreover, fluorene-based macromolecules which emit blue light (Jpn. J. Appl. Phys., 30, p.L1941 (1991)) have been reported but have disadvantages in that they cannot exhibit other various colors, and require the use of a manufacturing method, but by which macromolecules with more diversified conjugate double bonds cannot be made. The inventors of this application disclosed a fluorene-based alternating copolymer for an electroluminescence device having a conjugate double bond, which overcomes the above-described problems, in Korean Patent Application No. 96-16449 filed on May 16, 1996.
Meanwhile, macromolecules containing an acetylene group are disclosed in Makromol Chem. 191, p. 857 (1990), Macromolecules, 27, p 562 (1994), J. Chem. Soc., Chem. Commun., p 1433, (1995) and Macromolecules, 29, p 5157 (1996). However, these materials have been researched for applications for a non-linear optical material, an optical conductivity, and a photoluminescence (hereinafter, referred to as PL) Science, 279, p.835 (1998)). Recently, the present inventors have also proposed macromolecules containing acetylene groups, which are adapted for applications for LEDs, in Korean Patent Application No. 96-82444. Polymers having diacetylene groups have also been proposed (PROG. POLYM. Sci., 20, p.943 (1995), CHEMTECH, October, p.32 (1993) and Macromolecules, 29, p.2885 (1996)). Since such polymers having diacetylene groups are more sensitive to heat or light, cross linking reaction occurs therein easily. Such polymers are mainly applicable to non-linear optical materials, heat resistant macromolecules, polarized PL macromolecules, and electrically and optically active macromolecules. However, there is no application of such polymers to EL materials.
The present inventors have invented the present invention as a result of their active research to manufacture diverse kinds of macromolecular EL materials which require only a simple manufacturing method while exhibiting a definite structure in the final substance thereof and the materials being well soluble in any organic solvent.
Namely, the present invention is directed to using a polymer containing an acetylene group, as expressed by the following formula (I), to fabricate a macromolecular EL device. Since this polymer has an optical and electrical activity, thereby exhibiting PL characteristics, non-linear optical characteristics, and optical and electrical conductivity, it is expected that the polymer is applicable to photo switches, modules, waveguides, transistors, laser and light absorbers, and macromolecular separating membranes, all of which utilize those characteristics, in addition to applications to EL devices, in particular, LEDs , as mentioned above.
Therefore, an object of the present invention is to provide a light emitting material containing a new light emitting material.
Another object of the present invention is to provide an EL device made of the above mentioned light emitting material.
In accordance with the present invention, these objects are accomplished by providing a diacetylene-based polymer expressed by the following formula (I): 
wherein, Ar represents a light emitting group expressed by the following formulas:

wherein, R and Rxe2x80x2 are identical or different and are hydrogen, aliphatic or alicyclic alkyl or alkoxy groups containing 1 to 22 carbon atoms, aryl or aryloxy group containing 6 to 18 carbon atoms, or alkyl or aryl derivatives of silicon, tin or germanium; and n represents an integer equal to or greater than 1.